Incidence of polycyclic aromatic hydrocarbons in vegetable oil blends

The consumption of extra virgin olive oil has been growing in Brazil over the years. However, as it is an expensive product, many consumers tend to substitute extra virgin olive oil with a cheaper alternative, such as vegetable oil blends (mainly a mixture of olive and soybean oils). In the preset study, different brands of oil blends were evaluated for the occurrence of 13 polycyclic aromatic hydrocarbons. The method involved liquid–liquid extraction with hexane and N,N-dimethylformamide, followed by clean-up by SPE with C18 cartridges. Analyses were carried out by HPLC with fluorescence detection. PAHs were detected in all samples analyzed and the mean sum ranged from 2.59 μg/kg to 85.30 μg/kg. A high variability in PAHs levels between brands and between different batches of the same brand was observed. Approximately 50% of the samples were in disaccording with the maximum permitted levels for BaP and PAH4 established in the Brazilian and/or European regulations.     

Effect of natural antioxidants on the lipid oxidation of microencapsulated seed oil

Lipid oxidation was effectively prevented by natural antioxidants (NA) for surface free and encapsulated oils in microencapsulated seed oil (MESO) coated with dextrin and milk protein. Three kinds of NA were extracted from rosemary, broccoli sprout, and citrus, respectively. The antioxidant effect was significantly enhanced by the use of a mixture composed of 0.05% (w/w, oil based) rosemary, 1% broccoli sprout, and 1% citrus extract. The peroxide value (POV) of the total oil in the MESO was shown to lower to about 60 meq/kg even under the accelerated storage condition at 60 ± 1 °C for 30 days. The POV of total oil from MESO was 28.1 meq/kg in the presence of antioxidants, whereas the POV of the control sample without antioxidants reached 78.8 meq/kg. The present approach can find widespread use for preventing various microencapsulated seed oils from lipid oxidation.     

Changes in PAHs levels in edible oils during deep-frying process

Changes in the 16 PAHs in rapeseed, soybean, peanut and olive oil during deep-frying were examined to evaluate PAH levels in edible oils and the effects of deep-frying time. Chicken nuggets and potatoes were deep-fried in four types of oil for 15, 30 and 45 min. PAH concentrations were quantified via high-performance liquid chromatography (HPLC). The results show that all four fresh (unused) edible oils contain PAHs (189.9–2754.8 μg/kg) and mainly low-ring (2- to 4-ring) PAHs. PAH concentrations in the edible oils increased with increasing deep-frying time, especially among the high-ring (5-ring and above) PAHs. The mean values of high-ring PAHs (5-ring and above) in the samples deep-fried for 45 min were 1.9-fold higher than the oil samples that were deep-fried for 15 min and 31.5-fold higher than the levels for the fresh oils. The mean concentrations of benzo[a]pyrene in the deep-fried peanut and olive oils were 6.1- and 5.2-fold, respectively, the control value established in China (10 μg/kg). Average levels of ∑4PAH (consisting of benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) for the two deep-fried oils also exceeded the maximum permitted limit (10 μg/kg) set by the European Union (9.2- and 6.8-fold higher, respectively). At present, regulations imposed in China limit only concentrations of benzo[a]pyrene. The results of this study show that more standards and regulations on PAHs in edible oils must be established. In addition, the repeated use of edible oils must be avoided.     

The occurrence of volatile and semi-volatile aromatic hydrocarbons in virgin olive oils from north-eastern Italy

Twenty eight mono- (MAHs) and polyaromatic hydrocarbons (PAHs) were simultaneously determined in fifty-four virgin olive oils from three successive crops in the same geographical region. MAHs such as: toluene, C2-, C3- and C4-benzenes, and PAHs species containing 2, 3 and 4 aromatic rings were detected and quantified. MAHs were predominant in all of the samples, and had a mean concentration of 677 μg/kg. The mean concentration of total light PAHs was 80 μg/kg. Mean concentrations of C3- and C4-benzenes, which had not been previously quantified in olive oils, were 268 and 35 μg/kg, respectively. Finally, differences among crop years were evaluated, and the hypothetical daily intake of each aromatic hydrocarbon through virgin olive oil consumption was derived. The mean intake of single aromatic hydrocarbons ranged from 0.1 to 3.1 μg/day, while the mean exposures calculated for total MAHs and light PAHs were 15.6 and 1.8 μg/day, respectively.     

Evaluation of hydrocarbon contaminants in olives and virgin olive oils from Tunisia

The present paper investigated on the presence of some hydrocarbon contaminants, namely polycyclic aromatic hydrocarbons (PAHs), mineral oil hydrocarbons (MOH) comprising saturated (MOSH) and aromatic (MOAH) compounds, and polyolefin oligomeric saturated hydrocarbons (POSH) in olives and extra virgin olive oils from Tunisia. Olive fruits were collected in sites exposed to different environmental contamination, and the oil extracted both by physical mean (using an Abencor extractor) and with solvent (using microwave assisted extraction, MAE). Analytical determination was performed by SPE cleanup on silica cartridge followed by spectrofluorometric detection, for PAH, and on-line HPLC-GC-FID for MOH and POSH. Oils extracted from olives by physical mean, as well as extra virgin olive oils from the market, had PAH levels never exceeding the EU legal limits. All olive samples showed similar MOSH profiles, but not clear correlation between the variable contamination levels and considered sources of contamination, was evidenced. The average MOSH content in oil extracted from olives by solvent (11.1 mg/kg) was about four time higher than in oil extracted by physical mean (2.6 mg/kg). MOSH in extra virgin oil from the market ranged from 10.3 to 38.0 mg/kg, while MOAH were not detected. The higher MOSH levels found in oils from the market evidenced an important contribution due to oil processing and/or packaging. Two of the samples were clearly contaminated with polyolefin oligomeric hydrocarbons (POSH) migrated from the plastic cap.     

Fate of ochratoxin A during wheat milling and some Chinese breakfast processing

To estimate the dietary intake of ochratoxin A (OTA), information on the fate during wheat processing is needed. The wheat contaminated with OTA at both levels (93.22 and 248.93 μg/kg) was artificially inoculated by Aspergillus ochraceus. Concentrations of OTA were 1.43–1.66 times higher in bran than whole wheat and 1.27–1.50 times higher in shorts than bran. A concentration reduction of 43.29–55.16% for OTA in flour was observed, with the final concentrations of 41.80 and 138.33 μg/kg in flour respectively. Whereas, OTA was not transferred or decomposed during milling, as the total amount of OTA in all milling fractions didn't decreased. The further losses of OTA were various depending on different processes. The concentration of OTA increased by 11–16% when the flour was processed into Chinese steamed bread (CBS), with the OTA concentrations of 49.2 and 161.35 μg/kg in CBS. It revealed fermentation and steaming increased the OTA levels in CBS. The loss of OTA was small in the Chinese fried bread sticks (CFBS) (38.84 and 129.02 μg/kg), being of 6.73–9.63%. A higher reduction of 23.27–23.92% for OTA was detected in the noodles processing, with the final concentration of 32.98 and 108.24 μg/kg in noodles respectively. The result revealed that the temperature, pH values and strains involved the processes exerted different effects. High temperature (180 °C) and alkaline condition (pH > 7) facilitated to the removal of OTA, while fermentation (with dry yeast) increased the OTA levels in products.     

Application of low-resolution Raman spectroscopy for the analysis of oxidized olive oil

The aim of this study was to evaluate the potential of low-resolution Raman spectroscopy for monitoring the oxidation status of olive oil. Primary and secondary oxidation parameters such as peroxide value, K₂₃₂ and K₂₇₀ were studied. Low-resolution Raman spectra ranging from 200 to 2700 cm^?1 in a set of 126 oxidized and virgin olive oil samples were collected directly using a probe. Partial Least Squares was used to calibrate the Raman instrument for the different targeted parameters. The performance of the models was determined by using validation sets, and the best results obtained were: R² = 0.91, RMSEP = 2.57 for the peroxide value content; R² = 0.88, RMSEP = 0.37 for K₂₃₂; and R² = 0.90, RMSEP = 0.08 for K₂₇₀. These results demonstrated that low-resolution Raman spectroscopy could be a relevant technique for evaluating the oxidation status of olive oils because the key oxidation parameters can be determined quickly and in a non-destructive and direct way.     

Effect of packaging material headspace,oxygen and light transmission,temperature and storage time on quality characteristics of extra virgin olive oil

The effect of packaging parameters (transmission to light and oxygen, headspace volume) and storage temperature on quality characteristics of extra virgin olive oil (EVOO) was studied as a function of storage time (0–12 months). Packaging materials tested included clear glass, clear polyethylene terephthalate (PET), clear PET + UV blocker, clear PET covered with aluminum foil and clear polypropylene (PP) bottles. Quality parameters monitored over the 12 month storage period included: acidity, peroxide value (PV), spectrophotometric indices (K₂₃₂, K₂₇₀) and color. Results showed that the best packaging material for olive oil packaging was glass followed by PET. PP proved to be unsuitable for such an application. Exposure of olive oil samples to light, high storage temperatures (35 °C) and large headspace volumes caused substantial deterioration in product quality parameters. The most pronounced effect was that of temperature and light while the smallest effect was that of headspace volume and packaging material permeability to oxygen. Olive oil color was not substantially affected by storage conditions with the exception of storage of olive oil at 35 °C exposed to light for 12 months. Shelf life of extra virgin olive oil was 6 months packaged in clear glass in the dark at temperatures up to 22 °C; 3 months in clear PET in the dark at 22 °C and less than 3 months in clear PP in the dark at 22 °C. When exposed to light, shelf life of olive oil was 9 months when packaged in PET + aluminum foil; 3 months in PET + UV blocker and less than 3 months in clear PET at 22 °C. Product shelf life was less than 3 months at 35 °C. Finally oxygen in the headspace of olive oil resulted in deterioration of product quality. The relative contribution of parameters studied to the retention of olive oil quality was: temperature ≈ light > container headspace > packaging material oxygen permeability.     

Concentration and survey of phthalic acid esters in edible vegetable oils and oilseeds by gas chromatography-mass spectrometry in China

Now, there is a lack of information regarding the occurrence and the content of phthalic acid esters (PAEs) contamination in edible vegetable oils and oilseeds used for oil production in China. In this study, a method for determination of five PAEs was developed based on gas chromatography-mass spectrometry. Method recoveries for oils and oilseeds were 72.4–103.0% and 77.2–98.8%, respectively. RSDs of five analytes in oils and oilseeds were ranging from 1.22 to 8.64% and 0.62–9.37%, respectively. The LODs and LOQs were ranging from 0.10 to 0.79 and 0.33–2.60 μg/kg, respectively. Based on the established method, PAE concentrations in thirty-four edible oils and twenty-eight oilseeds were evaluated. Five and thirteen oil samples exceeded the upper limits 1.5 and 0.3 mg/kg set for di(2-ethtlhexyl) phthalate and dibutyl phthalate in China, respectively. The results obtained indicated that more concern and comprehensive legislation are still needed and mulriple issues should be considered when it comes to the PAEs contamination in edible vegetable oils.     

1H-NMR fingerprinting to evaluate the stability of olive oil

¹H-NMR fingerprinting is used to evaluate the stability of olive oil at room temperature while protected from light. Principal component analysis (PCA) of the ¹H-NMR spectral data allows to visualize the evolution of virgin olive oil (VOO) with time. The PCA loadings disclose the chemical compounds responsible for the compositional changes taking place in VOO. None of the ¹H-NMR signals present at time zero disappeared or experienced significant decreases or increases within the 3 years and seven months of the study. However, some small changes in the signals, and the appearance of some low intensity ones, indicate that some oxidative and hydrolytic degradation of the VOO started after one year. The presence of ¹H-NMR signals of hydroperoxides (primary oxidation products) with relative small intensities indicates that the oxidative degradation was taking place at a very low rate and yield. Moreover, the characteristic resonances of aldehydes (main secondary oxidation products) were not detected in the VOO over the studied time period, therefore the secondary oxidation process had not yet occurred. These results confirm the high oxidative stability of VOO at room temperature. On the other hand, slight changes in the ¹H-NMR signal intensity of tryglycerides and sn-1,3-diglycerides indicates that some hydrolytic degradation of the VOO had started.     

Rapid GC-FPD determination of organophosphorus pesticide residues in Sicilian and Apulian olive oil

A simple and quick method for the determination of dimethoate, parathion-methyl, fenthion, parathion-ethyl, and methidathion in olive oil is described. Analysis was carried out using GC (capillary column 5 m × 0.32 mm × 0.45 μm) with aspecific detector (FPD), after sample extraction with acetonitrile. No cleanup was necessary because there were no interferences in the chromatogram. Recoveries of five pesticides at three fortification levels (1.0, 0.2 and 0.05 mg/kg) were in the range 78–97%.Seventy-nine samples were collected from Sicilian and Apulian individual growers during 2002–2003. Only 16% of the samples contained fenthion in concentrations ranging from 0.09 to 0.73 mg/kg; no other pesticides were detected in the 79 samples.     

Survey of patulin in apple juice concentrates in Shaanxi (China) and its dietary intake

This study surveyed the patulin level in the apple juice concentrates from Shaanxi province for four consecutive processing seasons, and evaluated the dietary exposure to this mycotoxin through apple juice. A total of 1987 apple juice concentrate samples were analyzed by high-performance liquid chromatography with a diode-array detector, and only 4 samples in 2007–2008 processing season contained patulin above 50 μg/kg, the current regulatory limit in apple juice. The incidence of patulin contamination varied significantly from 96.7% to 100% (P < 0.05) by processing season, and the patulin level among the four processing seasons varied significantly with the median level from 6.30 to 8.90 μg/kg (P < 0.05, Kruskal–Wallis test). The highest evaluated patulin intake based on the apple juice consumption from the World Health Organization's Global Environment Monitoring System/Food Contamination Monitoring and Assessment Programme (GEMS/Food) was 1.04 ng/kg body weight (bw)/day in cluster diet F. And the patulin intakes for apple juice consumers among adults, children and babies were estimated to be 28.1, 67.5 and 110 ng/kg bw/day. All of the above values were well below the provisional maximum tolerable daily intake proposed by the Joint FAO/WHO Expert Committee on Food Additives.     

Antioxidant and anti-foodborne bacteria activities of shiitake by-product extract in fermented sausages

The effect of addition of extract from shiitake by-products (0, 0.3, and 0.6%) on the quality characteristics, lipid oxidation and microbial stabilities of fermented sausages was studied during storage up to 30 days at 15 °C, and its effect was also compared with those produced with synthetic antioxidant, BHT (0.02%) or nitrite (0.01%). The addition of natural extract resulted in lower ultimate pH values with higher number of lactic acid bacteria, lower lipid oxidation level and spoilage bacteria count in the products during storage as compared with those of the control or BHT and nitrite treatments (P < 0.05). Storage time significantly increased the lipid oxidation level, however, the increasing rate after 30 days storage in the following order: Control (increased by 1.22 mg MDA/kg) > 0.02% BHT (increased by 0.43 mg MDA/kg) > 0.01% nitrite/nitrate (increased by 0.42 mg MDA/kg) > 0.3% SSE (increased by 0.34 mg MDA/kg) > 0.6% SSE (increased by 0.18 mg MDA/kg). Furthermore, extract of fermented sausages fortified with 0.6% shiitake stipes extract also showed strong antimicrobial activity against 3 foodborne bacteria such as Staphylococcus aureus (minimum inhibitory concentrations (MIC) = 2.08 mg/mL), Listeria monocytogenes (MIC = 4.16 mg/mL) and Escherichia coli O157 (MIC = 8.33 mg/mL). Additionally, the addition of the extract did not cause defects of color, texture and sensory quality in the products. Our results clearly suggest that the shiitake by-product extract represents a functional ingredient to be used (at level of 0.6%) for improving lipid oxidation and microbial stabilities as well as controlling the growth of pathogens in fermented sausages.     

Co-exposures of aflatoxins with deoxynivalenol and fumonisins from maize based complementary foods in Rombo,Northern Tanzania

Children consuming maize based foods in Tanzania may be exposed to multiple mycotoxins. We estimated co-exposures of aflatoxins with Deoxynivalenol (DON) and fumonisins for children in rural Tanzania. Food consumption by the children was estimated by twice administering a 24 h dietary recall questionnaire to mothers of 18–24 months old children in Kikelelwa village. Each mother also, provided a sample of maize based flour used for feeding her child in the previous day. Each child's body weight (bw) was measured by following standard procedures. Aflatoxins, DON and fumonisins were determined in each sample using validated HPLC methods. Exposures for a mycotoxin were estimated by multiplying flour consumption (g/child/kgbw/day) by its contamination (μg/kg). Complete data were obtained for 41 children. Maize flour consumption ranged from 16 to 254 g/child/day. Thirteen (32%) of the 41 children consumed flour with detectable aflatoxin levels (range, 0.11–386 μg/kg), resulting in exposures from 1 to 786 ng/kg bw/day. All these children exceeded the aflatoxins exposure of concern (0.017 ng/kg bw/day). Eighteen (44%) of the children consumed flour with detectable DON levels (57–825 μg/kg) and 34 (83%), detectable fumonisins levels (63–2284 μg/kg), resulting in respective exposure ranges of 0.38–8.87 μg/kg bw/day and 0.19–26.37 μg/kg bw/day. Twelve (66%) of the DON exposed children and 56% of the fumonisins exposed children exceeded the respective provisional tolerable daily intakes of 1 μg/kg bw and 2 μg/kg bw. Co-exposures for aflatoxins with both DON and fumonsins were determined in 10% of the 41 children. Co-exposures of aflatoxins with fumonisins alone were found in 29% and of fumonisins with DON alone in 41% of the children. The study showed that children consuming maize based complementary foods in Northern Tanzania are at a risk of exposure to multiple mycotoxins. We recommend adoption of appropriate measures to minimize exposures of multiple mycotoxins in Tanzania.     

Incidence of aflatoxins contamination in dry fruits and edible nuts collected from Pakistan

During 2012–2015, a total of 624 samples of 13 different types of dry fruits and edible nuts were collected from retail shops and local markets of Pakistan. The collected samples were then studied for the occurrence of total aflatoxins (AFs) after immunoaffinity cleanup followed by HPLC coupled with fluorescence detector and post-column derivatization unit (Kobra Cell™). The seasonal variation of AFs was studied with respect to average temperature and relative humidity in Pakistan. LOD (S/N; 3:1) and LOQ (S/N; 10:1) of the utilized method were in the range of 0.09–0.12 and 0.30–42 μg/kg, respectively. About 165 (26%) samples were found contaminated, ranging from 0.22 to 30.11 μg/kg with a mean equivalent to 0.85 ± 0.26 μg/kg. In 459 (74%) samples, the AFs contamination was found lower than detectable limit corresponding to0.12 μg/kg. In 99 (15%) samples, the contamination range of AFs was 1–4 μg/kg. However, 28 (4%) samples exceeded the maximum tolerated limit (MTL) of 4 μg/kg as imposed by EU. However, 6 (1%) samples were found beyond the MTL of20 μg/kg as regulated by USA. Highly contaminated samples were found during the months of July, August and September. Achieved data highlighted the requirement of continuous monitoring and further investigation of AFs contamination in dry fruits/edible nuts under the authority of a definite systematic surveillance program adapted as a food safety measure.     

Effect of packaging and storage conditions on quality of shelled walnuts

The present study investigated the effect of packaging and storage conditions on quality of raw shelled walnuts. Walnut kernels were packaged in: (a) low density polyethylene (LDPE), 55 μm in thickness in air, (b) polyethylene terephthalate||polyethylene (PET||PE), 70 μm in thickness under N₂, and (c) PET-SiO_x||PE pouches, 62 μm in thickness under N₂. Samples were stored either under fluorescent light or in the dark at 4 or 20 °C for a period of 12 months. Quality parameters monitored were peroxide value (PV), hexanal, 2-thiobarbituric acid (TBA), odor, and taste of product. PV ranged between 0.3 for fresh walnut kernels and 31.4 meq O₂/kg oil for walnuts packaged in PE pouches exposed to light after 12 months of storage. Respective values for hexanal were <28.5 μg/kg and 36.0 mg/kg and for TBA ca. 0.2 and 11 mg MDA/kg. Values for odor ranged between 0.2 for fresh walnut kernels and 5.7 for walnut kernels packaged in PE exposed to light after 12 months of storage at 20 °C. Respective values for taste were 0.7 and 6.8. Taste proved to be a more sensitive attribute than odor. Based on shelf life (taste) values and PV data it is proposed that the upper limit value for PV is close to 10.0 meq O₂/kg walnut oil. Respective limit values for hexanal are 1–2 mg hexanal/kg walnut and for TBA is 1–2 mg malondialdehyde/kg walnut. Walnuts retained acceptable quality for ca. 2 months in PE-air, 4–5 months in PET||PE-N₂ and at least 12 months in PET-SiO_x||PE-N₂ pouches at 20 °C, with samples stored in the dark retaining slightly higher quality than those exposed to light. The effect of parameters investigated followed the sequence: temperature > degree of O₂ barrier > lighting conditions.     

Investigations on the occurrence of mycotoxins in beer

The occurrence of several mycotoxins, including ergot alkaloids, alternariol (AOH), deoxynivalenol (DON), and zearalenone (ZEA) in beer (n = 44) from the German market was studied by using enzyme immunoassay methods. Detection limits in beer were 2.1 μg/L (DON), 0.14 μg/L (ZEA), 0.06 μg/L (ergometrine equivalents), and 0.18 μg/L (AOH). DON was detected in 75% of the samples (2.2–20 μg/L, median 3.7 μg/L). All samples were positive for ZEA (0.35–2.0 μg/L, median 0.88 μg/L) and AOH (0.23–1.6 μg/L, median 0.45 μg/L). Most samples (93%) were positive for ergot alkaloids (0.07–0.47 μg/L, median 0.15 μg/L). Correlating toxin levels in beer with European Union tolerable daily intake (TDI) levels for DON (1 μg/kg b.w.), ZEA (0.25 μg/kg b.w.), and ergot alkaloids (0.6 μg/kg b.w.), beer does not represent a major source of intake of these toxins. No TDI data are available for AOH, but considering toxin levels in other foods, beer does not seem to be a major source of intake of this toxin either. Nevertheless, the frequency of their occurrence warrants further study of ergot alkaloids and AOH in raw materials used for beer brewing.     

A survey of the incidence and level of aflatoxin contamination in a range of locally and imported processed foods on Malawian retail market

Samples of locally (Malawian) processed and imported maize- and groundnut-based food products (peanut butters, roasted groundnuts, peanut based therapeutic foods, instant baby cereals, maize puffs and de-hulled maize flour) were collected from popular markets of Lilongwe City, Malawi. The samples were analysed in order to determine the frequency and extent of aflatoxin contamination, using immuno-affinity column and reversed-phase liquid chromatography with post-column photochemical derivatization and fluorescence detection. No aflatoxins were detected in all samples of imported baby cereal and locally processed de-hulled maize flour. However, all locally processed maize based baby foods had aflatoxins above EU maximum tolerable level of 0.1 μg/kg. In 75% of locally processed maize puffs, aflatoxins were detected at levels of up to 2 μg/kg. Peanut based therapeutic foods had aflatoxin level between 1.6 and 2.9 μg/kg, exceeding the EU tolerable maximum level (0.1 μg/kg) set for food for health purposes. Locally processed peanut butters had aflatoxins levels in the range of 34.2–115.6 μg/kg, which was significantly higher than their imported counterparts (<0.2–4.3 μg/kg). Samples of locally processed skinned and de-skinned roasted groundnuts had aflatoxins in range of 0.5–2.5 μg/kg and 0.6–36.9 μg/kg, respectively. These results highlight the need for rigorous monitoring of aflatoxins in commercially available processed products in order to reduce likely health risks associated with dietary aflatoxin intake.     

Stable isotope and fatty acid compositions of monovarietal olive oils: Implications of ripening stage and climate effects as determinants in traceability studies

The quantitative variability of isotopic and fatty acid compositions in extra virgin olive oil was investigated in relation to variety, olive ripeness index and geographical origin. The study was carried out in two environments of Umbria region (central Italy), differing in annual/seasonal temperatures and rainfalls. Significant correlation was found between oil isotope compositions and climatic seasonal changes during fruit ripening. Moreover, significant isotopic differences among cultivars were related to the period of maximum oil accumulation in the fruits and to the fatty acid profile. A carbon kinetic isotopic effect could be associated with the fatty acid elongation from palmitic to stearic acid and to the unsaturation step leading from oleic to linoleic. No correlation was found between stable isotope and fatty acid compositions during fruit ripening. The analyzed cultivar and ripening effects on oil traceability issues are discussed in order to focus the resolution power of stable isotope methodologies and the possibility to distinguish monovarietal oils from the same area.     

A Simple Colorimetric Enzymatic-Assay,based on immobilization of acetylcholinesterase by adsorption,for sensitive detection of organophosphorus insecticides in olive oil

Over the last decades, cholinesterase (ChE) biosensors/bioassays have emerged as an ultra sensitive and rapid technique for pesticides detection in environmental monitoring, food and quality control. In this work a Simple Colorimetric Enzymatic-Assay for the sensitive detection of three organophosphorus insecticides widely used in the treatment of olive trees: Malathion, Dimethoate and Methidathion in their oxidized form was developed. The systems are based on the immobilization of 0.3 mIU of electric eel acetylcholinesterase by adsorption on MaxiSorp™ microplates, and tested using standard solutions and real samples of olive oil. The developed colorimetric tests showed good analytical performances with limits of detection as low as 10⁻⁹ M for the widely used pesticide malaoxon (oxidized malathion), as well as a good reproducibility, good operational and storage stability and they can be applied directly on olive oil real samples without a laborious pre-treatment and after a simple liquid–liquid extraction, which demonstrate the potentiality of this technique to be used for commercial purpose.